An inorganic/organic hybrid perovskite compound, also referred to as an organometal halide perovskite compound, is represented by a chemical formula of AMX3, consisting of an organic cation (A), a metal cation (M), and a halogen anion (X), and having a perovskite structure. Specifically, the inorganic/organic hybrid perovskite compound represented by a chemical formula of AMX3 is in the form of a three-dimensional network in which an MX6 octahedron is corner-shared, and A, an organic cation is positioned at the center. The inorganic/organic hybrid perovskite compound has a characteristic of self-assembling crystallization, and thus, is advantageous in that a low-temperature solution process is possible. However, the compound has a problem in that a crystallization rate is very high, and it is difficult to control the self-assembling characteristic, so that it is difficult to manufacture a dense thin film having a flat surface in practice.
In order to solve the problem, a sequential deposition method wherein a solution of metal halide (MX2) is coated to form a metal halide film, an organic halide (AX) solution is coated on the metal halide film to form a laminate of MX2 and AX films, and then the two films are reacted to form an inorganic/organic hybrid perovskite compound film, has been suggested (Chem. Mater. 13, 3283 (2001)). However, this sequential deposition method has problems in that firstly, the solubility of MX2, represented by PbI2 is not sufficiently high so that the manufacture of a thick metal halide film problematic; secondly, even in the case of maintaining a MX2 solution at high temperature and coat it to obtain a thick film of 200 nm or more, MX2 is not sufficiently reacted with AX in a reaction step due to its thickness; and thirdly, in the case of a film manufactured by a conventional sequential deposition method, large volume change is caused when two films are reacted, so that the surface of a finally obtained inorganic/organic hybrid perovskite compound film has very high roughness. Particularly, the roughness of a film surface may be a critical factor to lower a performance index of a cell, in a solar cell provided with an inorganic/organic hybrid perovskite compound film as a light absorbing layer.